Regensburg 2022 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 13: Cytoskeleton

BP 13.8: Vortrag

Mittwoch, 7. September 2022, 11:45–12:00, H15

Microscopic modelling of forces and torques in the mitotic spindles — •Maja Novak¹, Arian Ivec¹, Iva M. Tolić², and Nenad Pavin¹ — ¹University of Zagreb, Faculty of Science, Bijenička c. 32, 10 000 Zagreb — ²Rudjer Bosković Institute, Biophysics of Cell Division, Bijenička c. 54, 10000 Zagreb

The mitotic spindle is a complex micro-machine built from microtubules and associated proteins, with a purpose to properly separate genetic material into two nascent cells. In our previous work we found that microtubule bundles in human spindles follow a left-handed helical path [1], from which we concluded that torques, in addition to forces, exist in the mitotic spindle. However, theoretical description of molecular origin of forces and torques in the mitotic spindle is still missing. Here we show that single-molecule rotational forces regulate the volume of mitotic spindle, where larger twisting moment increases the spindle width. Our model describes microtubules as flexible rods, which are cross-linked by the motor proteins and passive linkers. The model predicts angular distribution of microtubules at the pole, based on experimentally observed shapes of microtubule bundles in the spindle midzone. Finally we found that the bending and twisting moment at the pole change between the inner and outer bundles in a manner qualitatively similar to curvature and twist obtained from the experimental data. In conclusion, our microscopic description opens up the possibility to quantify and understand both function and details of the twisting moment in the mitotic spindle. [1] Novak et al., Nat. Commun.(2018)9:3571